As smartphones and tablet terminals have become widespread, the amount of mobile communication data traffic has greatly increased. As a result, LTE (Long Term Evolution) communication that realizes a higher speed and a larger capacity has also become widespread. In addition, LTE-Advanced (hereinafter, LTE-A) that realizes an even higher speed is being introduced. An LTE/LTE-A network includes a wireless network (E-UTRAN (Evolved Universal Terrestrial Radio Network) and a core network (EPC (Evolved Packet Core)). The E-UTRAN includes a base station(s) and terminals. The EPC includes a P-GW (PDN (Packet data network) Gateway) for establishing connection with an external network such as the Internet and an S-GW (Serving GW) that handles the U-plane (User plane) for user data, for example. In an LTE/LTE-A network, from a viewpoint of improvement of the frequency usage efficiency, a packet switching-over method in which a band is frexibly allocated is used, and voice can be packetized by using VoIP (Voice over IP).
In LTE, nine QCIs (QoS Class Identifiers) are defined as parameters for managing QoS (Quality of Service). The presence or absence of band control (GBR (Guaranteed Bit Rate) or Non-GBR), a priority, a PDB (Packet Delay Budget), a Packet Loss Rate, etc. are defined per QCI. Rules defining which QCI needs to be allocated to which service are set by PCRF (Policy Charging Rule Function) for EPC. The P-GW performs QoS control based on the rules set by the PCRF. In an LTE network, a route (bearer), which is a virtual data path, is set between a P-GW and a wireless terminal per QCI. A scheduler of a radio base station refers to the QCI information and checks the priority of an individual packet to be transmitted to a wireless terminal. In view of the priority, the scheduler determines the order of the transmission of the packet to the wireless terminal and the amount of radio resources to be allocated (NPL 1). The table in FIG. 27 illustrates an example in which the QCIs are defined. In this example, Conversational Voice is defined as a service transmitted through a bearer whose QCI is 1. In addition, Video, TCP-based, etc. are defined as services transmitted through a bearer whose QCI is 8. For example, when a wireless terminal #1 is waiting to receive packet data whose QCI is 1 and a wireless terminal #2 is waiting to receive packet data whose QCI is 8, priority control using the QCIs is performed. In this case, the packets addressed to the wireless terminal #1 waiting for packet data whose priority is higher (QCI=1) are transmitted preferentially. From the viewpoint of the PDB, if there is not enough wait time for the packets whose QCI is 8, the packets addressed to the wireless terminal #2 may preferentially be transmitted, too.    NPL 1: 3GPP TS23.203 v11.13.0 (2014-03), Policy and charging control architecture, p. 38.    NPL 2: 3GPP TS23.401 v12.5.0 (2014-6) UE-PGW user plane with E-UTRAN, p. 82.    NPL 3: RFC793, TRANSMISSION CONTROL PROTOCOL DARPA INTERNET PROGRAM PROTOCOL SPECIFICATION, September 1981    NPL 4: RFC791, INTERNET PROTOCOL DARPA INTERNET PROGRAM PROTOCOL SPECIFICATION, September 1981